1. Field of the Invention
The present invention relates generally to the formation of an inner circumferential groove in a pipe section and more particularly to a specific assembly for and specific methods of providing an inner circumferential groove in the bell end.
2. Description of Prior Art
Heretofore, there have been many suggested methods of seal connecting together two pipes. One such method utilizes a bell and spigot joint which includes a female counterpart member, commonly referred to as the bell end, having an enlarged sleeve defining an inner circumferential groove. An annular sealing gasket is provided within the groove and coaxial with the pipe. In this manner, the male counterpart member, commonly referred to as the spigot, can be inserted into the bell end with the gasket providing a seal therebetween.
There are many methods of forming the aforedescribed bell end and particularly the inner circumferential groove in the bell end. For example, U.S. Letters Pat. No. 3,520,047 issued to Muhlner et al discloses one method wherein the sealing gasket and a pair of retainer rings are positioned around the external surface of an elongated core. A thermoplastic pipe, which has been heated to its deformable state, is deformed concentrically around the core, gasket and support ring and allowed to cool. In this manner, a bell end is formed and includes an annular furrow defining an inner circumferential groove around the gasket and support rings.
Another method of forming an inner circumferential groove is disclosed in U.S. Letters Pat. Nos. 3,205,535 and 3,264,383, both being issued to Niessner et al. In these patents, a cylindrical core is provided including circumferentially spaced core sections which are movable in radial planes through the axis of the core. The heated end section of a pipe is deformed around the core and core sections, with the core sections being in radially extended positions, thereby forming a bell end including an inner circumferential groove. After the bell end is cooled, the core sections are moved in a radial direction inwardly for withdrawal of the core from the formed bell end.
As will become apparent hereinafter, the present invention provides a different method and assembly for forming an inner circumferential groove in a pipe section, the method and assembly of the present invention being both reliable and uncomplicated in design.